Electron Correlation Studies of Weakly Bonded Systems

Spin-adapted Coupled Cluster Double Substitution (CCD) theory is developed and the matrix operators of Pair Operator Formalism are derived. The set of equations for the CCD coefficients is related to a full variational solution of the CCD wavefunction. An approximation to CCD theory (ACCD) is developed and compared to the CEPA approximations. The SCEP, CEPA, and CCD potential energy curves of the closed shell dimers of the homo-nuclear series He(,2), Be(,2), and Mg(,2) and the hetero-nuclear series HeBe, HeMg, BeMg are reported. The SCEP and CCD curves are similar suggesting that the size-consistency error is of minor importance. The CEPA-0 potential curves of the Be dimers have deep, close-in wells while the SCEP and CCD potential curves have shallower wells. SCEP and CEPA-2 calculations are also reported for Mg(,4). The Mg(,4) species is found to be chemically bonded due to the correlation effects of the d orbitals.

Name thesis:degree_name

Ph.D.

Level thesis:degree_level

Dissertation

Discipline thesis:degree_discipline

Chemistry

Grantor

University of Illinois at Urbana-Champaign

Year dc:date

2014

Author dc:creator

• Chiles, Richard Andrew

• Chemistry, Physical

Identifier

(UMI)AAI8302831

OAI identifier oai:identifier

oai:www.ideals.illinois.edu:2142/70194